With the recent advent of digital TV, etc., technology in the broadcasting TV and home entertainment fields are abruptly being developed. Technology of the fields is being commercialized by the standardization of video compression technology. For video compression, an ITU-T (International Telecommunications Union-Telecommunication) H.263 standard is being widely used. MPEG-4 which is the next standard of MPEG (Motion Picture Experts Group) is being used for Internet-based video applications.
After the H.263 standard was completed, ITU-T VCEG (Video Coding Experts Group) has devoted itself to achieve a short-term target for adding additional characteristics to the H.263 standard and a long-term target for developing a new standard for visual communication of a low bit rate. In the year of 2001, JVT (Joint Video Team) consisting of the experts of MPEG and VCEG was constructed, and the JVT has performed a standardization task of ITU-T H.264/MPEG-4 part 10 which is a new standard for the coding of video. The H.264 standard may also be called AVC (Advanced Video Coding). The technological target of the H.264/AVC is for the significant improvement of coding efficiency, coding technology robust to loss and error, network-friendly coding technology, low latency capability, accurate match decoding, and so on.
Most of surrounding pixels within video have similar values. The same principle applies to 4×4 blocks or 16×16 blocks which are a minimum block size of the H.264/AVC standard. Prediction for the video may be performed using the likeness between inter-block values as described above, and a difference between the video and an original video can be encoded. This is called intra-prediction. The efficiency of video coding can be increased by intra-prediction.
Furthermore, in performs intra-prediction, a filter may be applied before the intra-prediction is performed. In typical cases, when intra-prediction is performed in the H.264/AVC standard, a filter is applied to reference pixel values, and the values to which the filter has been applied are used for the intra-prediction. However, the performance of video coding may be increased when the intra-prediction is performed without applying the filter rather than when the intra-prediction is performed after the filter is applied, according to circumstances.
Accordingly, there may be proposed a method of determining whether to apply a filter when performing intra-prediction.